FR3103228A1 - ENGINE MODE END OF CONTROL MODULE AND MANAGEMENT PROCESS FOR A ROTATING ELECTRIC MACHINE - Google Patents

Abstract

CONTROL MODULE AND PROCESS FOR MANAGING THE END OF ENGINE MODE FOR A ROTATING ELECTRIC MACHINE One aspect of the invention relates to a control module for a rotating electrical machine for a motor vehicle, the control module comprising a calculation program, a value of the rotor coil voltage Vrot, a resistance value of the rotor coil Rrot, a value of the rotor coil induction Lrot and in that the program estimates the rotor coil current Irot according to this formula: Irot [k] = Irot [k -1] + (Vrot [k-1] - Irot [k-1] x Rrot) / Lrot x Ts in which: o Irot [k-1] is the estimate of the rotor coil current previously calculated at time k -1 o Ts is the sampling time between the index k-1 and the index k, and in which to switch from a motor mode to a neutral mode, said control module is configured to command a shorting -circuit of the phases of the stator after the estimated rotor coil current Irot is equal to a predetermined value. Figure to be published with the abstract: Figure 3

Description

CONTROL MODULE AND METHOD FOR END OF MOTOR MODE MANAGEMENT FOR A ROTATING ELECTRIC MACHINE

The technical field of the invention is that of controlling rotating electrical machines.

The present invention relates to a method for managing end of motor torque for a rotating electrical machine.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

In a manner known per se, a reversible electric machine can be coupled to the heat engine, in particular via the accessory front. This electric machine, commonly called an alternator-starter, is capable of operating in a generator mode to recharge a vehicle battery as well as in a motor mode to provide torque to the vehicle.

The generator mode can be used in a regenerative braking function enabling the electric machine to supply electrical energy to the battery during a braking phase. The engine mode can in particular be used in an automatic stopping and restarting function of the heat engine depending on the traffic conditions (function called STT for "stop and start" in English), a function of assistance with the stalling of the heat engine , a so-called "boost" function allowing the electric machine to punctually assist the internal combustion engine during a rolling phase in thermal mode, and a freewheeling function, called "coasting" in English, allowing to automate the opening of the traction chain without explicit action by the driver to reduce the engine speed or stop it in order to minimize fuel consumption and polluting emissions. In addition, the motor mode can be used in electric vehicle mode in which the electric machine provides the torque necessary to move the vehicle forward without the torque provided by the heat engine.

In known machines, stopping the motor mode when a protection (thermal, time or speed) is activated causes the switching elements of the inverter of the electric machine to open. The current contained in the stator is then sent back to the vehicle's on-board network, causing a torque surge at the level of the accessories front panel and an overvoltage on the on-board network.

There is thus a control unit comprising an algorithm for torque management when stopping the motor mode to avoid these jerks by passing through a neutral mode. The control unit transmits a torque setpoint and a torque gradient according to a speed to bring the rotor current and then the stator voltage to zero at this same speed.

To bring the rotor current to zero, to exit motor mode quickly, a rotor voltage setpoint is set to zero by carrying out slow demagnetization in a closed loop or equal to minus U _B+ (U _B+ being the voltage at the machine terminals ), in order to impose a rapid demagnetization which will lower the current in the rotor. In rapid demagnetization, the coil of the rotor finds itself powered in reverse of the motor mode, which demagnetizes more quickly.

The demagnetization time depends on the rotor speed.

Then, once the rotor has been demagnetized, to avoid returning the current to the network, a short-circuit is made between the phases of the stator, for example by closing the low-stage MOSFETs of the inverter/rectifier, for a duration predetermined by example of about 10ms so that the residual current in the stator is eliminated in joule losses in the stator coils.

Nevertheless, this exit from motor mode often causes an oscillation of the torque and an overvoltage on the electrical network during the stator short-circuit and the zero current setting of the rotor for the transition to neutral mode. Indeed it regularly happens that the short-circuiting of the stator takes place while there is still current in the rotor.

One solution would be to wait for the worst case demagnetization time to short out the stator. However, this will slow down the transition from engine mode to neutral mode, which can hinder the driver's feeling.

There is therefore today a compromise between speed of the transition to neutral or jerk mode and overvoltage.

Another solution would be to have a measurement of the current of the inductive coil of the rotor, for example using a resistor in series with the inductive coil of the rotor and a voltage measurement unit on this resistance. However, such resistance leads to heating through joule losses and reduces the efficiency of the machine. Also, the demagnetization time is very long because at the end of the demagnetization, the rotor current decreases very slowly.

There is therefore a need to reduce or cancel the torque oscillation and an overvoltage on the electrical network for the transition from motor mode to neutral mode.

The invention offers a solution to the problems mentioned above, by considering the dynamics of the rotor making it possible to have a better simulation of the demagnetization slope of the rotor and therefore to short-circuit the stator when the rotor has less current than in the prior art without having too much delay.

One aspect of the invention relates to a control module for a rotating electrical machine for a motor vehicle comprising a rotor coil and phases of a stator supplied by an electrical network, the control module comprising a calculation program, an input comprising the voltage of the electrical network, a resistance value of the rotor coil, a value of the rotor coil induction and in that the program estimates a rotor coil current estimated according to this formula:

Irot[k] = Irot[k-1] + (Vrot[k-1] – Irot[k-1] x Rrot)/Lrot x Ts

in which :

Irot[k-1] is the estimate of the rotor coil current previously calculated at time k-1

Vrot [k-1] is the previous rotor coil voltage at time k-1

Ts is the sampling time between index k-1 and index k,

and in which to switch the electric machine from a motor mode to a neutral mode, said control module is configured to command a setting to the same potential of the phases of the stator after the estimated rotor coil current is equal to a predetermined value, by example 0 amps.

Thanks to the invention, the fact of estimating the current of the rotor considered as the indicator for the finalization, it is possible to switch to neutral mode when the current of the rotor is almost zero. Thus, it is possible to reduce or even eliminate the jerks and eliminate the overvoltages by improving the reduction in the current of the rotor and the reduction in the stator closest to zero at the same time. Indeed, the current and voltage peaks of the DC bus decrease in the transition from motor mode to neutral mode, the oscillations of the phase current and of the excitation are reduced or even disappear, and therefore the torque surges which are bound are diminished. In addition, the time to exit from motor mode to neutral mode is reduced considerably.

In addition to the characteristics which have just been mentioned in the previous paragraph, the control module according to one aspect of the invention may have one or more additional characteristics among the following, considered individually or in all technically possible combinations:

According to one embodiment, the control module for a rotating electrical machine comprises a memory storing software instructions for implementing the calculation of the estimated rotor coil current and the rotor and stator commands as previously defined.

According to an embodiment of the control module, to switch from a motor mode to a neutral mode, the control module is configured to produce a stator command according to the estimated rotor coil current.

According to one embodiment, the previously calculated rotor coil voltage is equal to a predetermined value, for example zero volts or minus eleven point three volts.

According to another embodiment, the control module includes a network voltage input (Vdc) and in that the previously calculated rotor coil voltage is equal to 0V or is calculated by the control module according to this formula:

Vrot[k-1] = -1 x (Vdc[k-1] – Vdiode),

Where Vdiode is a constant equal to for example zero point seven volts.

The invention also relates to a rotating electrical machine comprising a control module according to the previous embodiment, comprising:

a rotor comprising an inductive coil,

a stator comprising a winding having phases, and

a rotor control unit comprising:

a high stage electronic switch connected between the input of the inductive coil and the positive terminal of the network,

a low electronic switch between ground and the inductive coil input,

a low output electronic switch between the output of the inductive coil and ground,

a diode comprising a cathode connected to the positive terminal of the network and an anode connected to the output of the inductive coil,

in which the rotor control unit can control in the event of a motor mode stop command, either according to a fast demagnetization setpoint, the closing of the low electronic switch, the opening of the low output electronic switch and the opening of the high stage electronic switch, either according to a slow demagnetization setpoint, closing of the low electronic switch, closing of the low output electronic switch and opening of the high stage electronic switch,

in which, in the event of a fast demagnetization setpoint, the previous rotor coil voltage is calculated according to the formula:

Vrot[k-1] = -1 x (Vdc[k-1] – Vdiode), and

in the case of a slow demagnetization setpoint, the rotor coil voltage is equal to zero.

According to one embodiment of the electric machine, the rotating electric machine comprises a temperature sensor, in which the value of the rotor resistance is estimated as a function of the temperature measured by the temperature sensor.

For example the value of the rotor resistance is according to this formula Rrot = R0(1 + αv.ΔT)

Where R0 is a resistance value of the coil at a predetermined temperature, ΔT(K) is the temperature variation between the predetermined temperature and the temperature measured by the temperature sensor and αv is a predetermined isobaric volume expansion coefficient, equal to for example 0.0039 to 0.008 and advantageously 0.00396.

Indeed the resistance of the rotor varies mainly according to the temperature of the rotor.

According to another embodiment of the electric machine, the value of the rotor resistance is a predetermined value.

Thus according to these two embodiments, to estimate the rotor current, either a value equivalent to the rotor coil resistance or an estimated value of the rotor resistance is calculated.

According to one embodiment of the electric machine, further comprising a rotor rotation speed sensor and in that the value of the rotor coil induction is estimated as a function of an operating point of the machine estimated from the estimated or setpoint rotor torque and rotational speed.

According to another embodiment of the electric machine, the control module estimates the speed of rotation of the rotor and in that the value of the rotor coil induction is estimated as a function of an operating point of the machine estimated from of the estimated or setpoint rotor torque and the estimated rotational speed.

Indeed, the rotor inductance varies according to the magnetic saturation, so an estimate of the rotor inductance is calculated to improve the accuracy of the estimated rotor coil current.

According to another embodiment, the value of the rotor coil induction (Lrot) is an equivalent value for finalization.

According to one embodiment of the rotating electrical machine, the control module comprises a transmission step for controlling the stator, of a setpoint torque Tem[k] according to this formula: Tem[k]=Tem_0 x (Irot[ k] / Irot_0)^2

where the rotor current Irot_0 is the estimated rotor current when the control module receives the motor mode stop command and Tem_0 is the electromagnetic torque of the machine when the control module receives the stop command setpoint engine mode.

According to one embodiment of the rotating electric machine, the electric machine comprises a voltage converter comprising high electronic switches and low electronic switches connected to the phases of the stator and in that when the control module receives a stop command from the previously activated motor mode, the control module transmits a stator command to modify the pulse width modulation of the high side electronic switches and the low side electronic switches depending on the estimated rotor current, such as plus the estimated rotor current , is low, the more the pulse width modulation is reduced to reduce the power supply of the phases of the stator in effective voltage.

According to an example of this embodiment and of the preceding embodiment, the stator control is a function of the calculated setpoint torque Tem[k], for example the calculated setpoint torque Tem[k].

According to one example, the electric machine comprises a stator control unit for controlling the high and low side switches by pulse width modulation and in that the pulse width modulation is parameterized according to the stator control.

• une étape d’estimation du courant bobine rotor (Irot[k) suivant cette formule : Irot[k] = Irot[k-1] + (Vrot[k-1] – Irot[k-1] x Rrot)/Lrot x Ts
  • dans lequel :
  • Irot[k-1] est l’estimation du courant bobine rotor préalablement calculé à l’instant k-1
  • Vrot [k-1] est la tension bobine rotor précédente à l’instant k-1
  • Ts est le temps d’échantillonnage entre l’indice k-1 et l’indice k,
• une étape de réception de commande d’arrêt moteur, comprenant :
  • une sous étape de démagnétisation commandant l’ouverture de l’ interrupteur électronique étage haut et la fermeture de l’interrupteur électronique bas, soit selon une consigne de démagnétisation rapide, en commandant l’ouverture de l’interrupteur électronique sortie bas ,ou soit selon une consigne de démagnétisation lente, en commandant la fermeture de l’interrupteur électronique sortie bas et
  • une sous étape de commande de mise au même potentiel des phases du stator après que le courant bobine rotor estimé est égal à une valeur prédéterminée.

Another aspect of the invention also relates to a method for stopping a motor mode of the rotary electrical machine previously described with or without the different embodiments, comprising:

• a step for estimating the rotor coil current (Irot[k) according to this formula: Irot[k] = Irot[k-1] + (Vrot[k-1] – Irot[k-1] x Rrot)/Lrot x Ts
  • in which :
  • Irot[k-1] is the estimate of the rotor coil current previously calculated at time k-1
  • Vrot [k-1] is the previous rotor coil voltage at time k-1
  • Ts is the sampling time between index k-1 and index k,
• an engine stop command reception step, comprising:
  • a demagnetization sub-step controlling the opening of the high stage electronic switch and the closing of the low electronic switch, either according to a fast demagnetization instruction, by controlling the opening of the low output electronic switch, or either according to a slow demagnetization setpoint, by controlling the closing of the low output electronic switch and
  • a control sub-step for bringing the phases of the stator to the same potential after the estimated rotor coil current is equal to a predetermined value.

• une étape de calcul d’un couple de consigne (Tem[k]) suivant cette formule :Tem[k] = Tem_0 x (Irot[k] / Irot_0)^2
  • où le courant rotor Irot_0 est le courant rotor estimé au moment où le module de contrôle reçoit la commande d'arrêt du mode moteur et Tem_0 est le couple électromagnétique d’une consigne au moment où le module de contrôle reçoit la consigne de commande d'arrêt du mode moteur, et
• une étape de commande du stator en fonction du couple de consigne jusqu’à ce que le courant bobine rotor estimé est égal à une valeur prédéterminée.

According to an embodiment of the preceding method, the method further comprises:

• a step for calculating a setpoint torque (Tem[k]) according to this formula: Tem[k] = Tem_0 x (Irot[k] / Irot_0)^2
  • where the rotor current Irot_0 is the estimated rotor current when the control module receives the motor mode stop command and Tem_0 is the electromagnetic torque of a setpoint when the control module receives the command setpoint from stopping the motor mode, and
• a step of controlling the stator as a function of the setpoint torque until the estimated rotor coil current is equal to a predetermined value.

The invention and its various applications will be better understood on reading the following description and examining the accompanying figures.

• La figure 1 représente un schéma de principe d’un système électrique SE d’un stator.
• La figure 2 représente un schéma de principe électrique d’un système d’alimentation d’un rotor.
• La figure 3 représente schématiquement des blocs d’un diagramme selon un premier exemple de ce mode de réalisation.
• La figure 4 représente schématiquement des blocs d’un diagramme selon un deuxième exemple de ce mode de réalisation.
• La figure 5 représente schématiquement des blocs d’un diagramme selon un troisième exemple de ce mode de réalisation.
• La figure 6A représente un histogramme représentant graphiquement la tension réseau Vdc, le courant du réseau électrique Idc, le courant du rotor Iexc [A] réel et Iph [A] le courant d’une phase du stator selon l’art antérieur.
• La figure 6B représente un histogramme représentant graphiquement la tension réseau Vdc, le courant du réseau électrique Idc, le courant du rotor Iexc [A] réel et Iph [A] le courant d’une phase du stator de la machine électrique selon le premier exemple du mode de réalisation décrit précédemment.

The figures are presented by way of indication and in no way limit the invention.

• FIG. 1 represents a block diagram of an electrical system SE of a stator.
• FIG. 2 represents an electrical block diagram of a rotor supply system.
• FIG. 3 schematically represents blocks of a diagram according to a first example of this embodiment.
• FIG. 4 schematically represents blocks of a diagram according to a second example of this embodiment.
• FIG. 5 schematically represents blocks of a diagram according to a third example of this embodiment.
• FIG. 6A represents a histogram graphically representing the network voltage Vdc, the electrical network current Idc, the actual rotor current Iexc[A] and Iph[A] the current of a phase of the stator according to the prior art.
• FIG. 6B represents a histogram graphically representing the network voltage Vdc, the electrical network current Idc, the real rotor current Iexc [A] and Iph [A] the current of a phase of the stator of the electric machine according to the first example of the embodiment described above.

The figures are presented for information only and in no way limit the invention.

The electrical machine is intended to be installed in a vehicle comprising an on-board electrical network connected to a battery.

The on-board network may be of the 12V, 24V or 48V type. The electric machine is coupled to a heat engine in a manner known per se by a belt or chain system located on the accessories front. In addition, the electric machine is capable of communicating with an engine computer using a communication protocol of the LIN type ("Local Interconnect Network" in English or "Local Internet Network" in French) or CAN ("Controller Area Network" in English which is a serial system bus) or Ethernet. The electric machine can operate in motor mode and can operate in alternator mode also called generator mode. In the case where the machine can operate in alternator mode, the electrical machine is an alternator-starter.

The rotating electrical machine M comprises a stator having at least three phases U, V, W and three coils u, v, w wound in the stator.

According to one implementation of these embodiments, the rotating electrical machine is an alternator-starter.

The alternator-starter comprises in particular an electrotechnical part and a control module according to the invention described in more detail below. More precisely, the electrical engineering part comprises an induced element and an inductor element. In one example, the armature is the stator, and the inductor is a rotor comprising an excitation coil, hereinafter called rotor coil Lrotor. The stator comprises a number N of phases. In the example considered, the stator comprises the three phases U, V, W. In this example, the coils u, v, w are connected in a star and each comprise at their output the corresponding phase U, V, W respectively. According to another example, the electric machine comprises six phases.

As a variant, the number N of phases may be equal to 5 for a five-phase machine, to 6 for a six-phase or double three-phase type machine or to 7 for a heptaphase machine. The phases of the stator can be coupled in delta or in star. A combination of delta and star coupling is also possible.

shows a schematic diagram of an SE electrical system of a stator. The electrical system SE comprises a first power supply terminal B+ and a second power supply terminal B- connected to a DC power source B, in this case in this example of 48 Volts, but can for example be 12 Volts or 24Volts, for example a battery of a motor vehicle making it possible to supply other electrical equipment, not shown, of the vehicle via an on-board network.

The DC power source B can also comprise the battery of a motor vehicle and a block of capacitors connected in parallel with the battery of the vehicle. In this example, the second terminal B- is the electrical system ground SE.

The electrical system SE further comprises a voltage converter O to supply the rotating electrical machine M from said DC voltage source B.

The voltage converter O comprises a plurality of switching arms connected in parallel, to the same number as the phases of the rotating electrical machine M. In this case the voltage converter O comprises a first arm X, a second arm Y and a third arm Z, but could include for example six in the case of the example of a six-phase rotating electrical machine.

Each arm X, Y, Z comprises a high side switch HS_X, HS_Y, HS_Z together forming a high group HS and a low side switch LS_X, LS_Y, LS_Z together forming a low group LS. Each high side and low side switch of an arm X,Y,Z are connected to each other at a midpoint PX, PY, PZ.

In this example, each high-side or low-side switch is a metal-oxide field-effect transistor each comprising a free-wheeling diode.

In this case, in this example, there is therefore on the first arm X a first high side switch HS_X connected to a first low side switch LS_X by a first midpoint PX, on the second arm Y a second switch of high side HS_Y connected to a second low side switch LS_Y by a second midpoint PY and a third high side switch HS_Z, respectively connected to a third low side switch LS_Z by a third midpoint PZ.

Each midpoint PX, PY, PZ is connected to at least one phase U, V, W of said rotating electrical machine M, i.e. in this example the first midpoint PX to phase U, the second midpoint PY at phase V and the third midpoint Z at phase W.

The voltage converter O further comprises a control unit U of the high side switches HS_X, HS_Y, HS_Z and of the low side LS_X, LS_Y, LS_Z. Said control unit U therefore comprises for each switch an output connected to the control of the corresponding switch. In order not to overload FIG. 1, only the connection between an output of the control unit U and the control of the third switch on the low side LS_Z and another output of the control unit U and the control of the second switch on the low side high HS_Y have been represented.

The control unit U controls the switches of each arm X, Y, Z in PWM pulse width modulation, better known by the acronym "PWM" for "Pulse Width Modulation".

There shows an electrical block diagram of a rotor power system.

The rotor power supply system comprises a power supply line making it possible to supply a load, in this case the rotor coil Lrotor from a voltage source, in this case the continuous power source B.

Said power supply line comprises a main switch Q1 having a first main terminal D and a second main terminal S between which a main current Ip is intended to pass.

The main switch Q1 further comprises a control terminal G to selectively put the main switch Q1 in a closed, open or semi-closed state. The main switch Q1 in its semi-closed state is equivalent to a variable resistor connected between the first D and the second main terminal S controlled by the control terminal G. In this case, the main switch Q1 is a transistor of power. More precisely, the power transistor is a metal-oxide gate field effect transistor also known by the acronym MOSFET and is in this case enrichment.

The power line is a high side switch system 1 forming part of a switching arm of an electrical system.

The switch arm comprises a low side switch system comprising a low side switch Q23 also comprising a first and second main terminal controlled by a control terminal.

The low side switch Q23 and the main switch Q1 is a high side switch Q1 and are connected to a middle point.

The low side switch Q23 is mounted between the midpoint and a negative terminal B- which may be vehicle ground.

The rotor coil Lrotor includes a terminal connected to the midpoint.

The electrical system further comprises a low output electronic switch Q24, also called demagnetization, also comprising a first and second main terminal, mounted between the negative terminal and the other terminal of the excitation coil and is controlled by a terminal of order.

The electronic demagnetization switch Q24 is controlled by the control module in saturated mode when the electric machine is in alternator mode or in motor mode or to demagnetize the excitation coil.

The low-side electronic switch Q23 together with the electronic demagnetization switch Q24 allows a controlled demagnetization of the Lrotor coil when the main switch Q1 is open.

The rotor power supply system further comprises in this embodiment, a diode D1 between the B+ terminal and the second terminal of the rotor coil Lrotor.

This diode D1 allows fast demagnetization of the rotor by closing the low side switch Q23 and opening the demagnetization switch Q24.

The control module comprises an excitation circuit integrating a chopper to generate an excitation current which is injected into the rotor coil Lrotor.

The rotating electrical machine comprises a motor mode, neutral and can comprise an alternator mode.

The control module further comprises a control circuit comprising a memory and for example a microcontroller.

The control module comprises a motor algorithm able to generate a stator command and a rotor command from a torque setpoint to be applied to the rotating electrical machine to put it in a motor mode. For example, following a request to activate an engine mode of the rotating electrical machine, in particular when starting a heat engine of a motor vehicle, said method comprises a step of applying a torque of setpoint and a setpoint torque gradient transmitted by an engine computer of the motor vehicle.

In this embodiment, the control module can control the control unit U to control the switches of the voltage converter O to control the stator.

In another embodiment, the control module is the control unit U.

The control module can therefore also control the switches Q1, Q23, Q24 of the rotor supply system.

The present invention aims to reduce or cancel an oscillation of the torque and an overvoltage on the electrical network when switching from motor mode to neutral mode.

The control module comprises in this embodiment an input for measuring the voltage of the electrical network Vdc, corresponding to the voltage of the DC power source.

The control module includes a rotor coil resistance value Rrot, a rotor coil induction value Lrot.

There schematically represents blocks of a diagram according to a first example of this embodiment.

In the first embodiment in which the control module receives as input the resistance value of the rotor coil Rrot and the value of the rotor coil induction Lrot. Each of these two values can be a predetermined fixed value or a value calculated and transmitted to the control module.

The control module includes a memory storing software instructions for calculating an estimation of a rotor coil current (Irot [k).

The estimated rotor coil current is calculated using this formula:

where Irot[k-1] is the estimate of the previously calculated rotor coil current at time k-1, Vrot[k-1] is the previous rotor coil voltage at time k-1

Ts is the sampling time between index k-1 and index k,

The electric machine comprises a motor mode and a neutral mode, and in that to switch from a motor mode to a neutral mode, said control module is configured to command setting the phases of the stator to the same potential after the coil current estimated rotor (Irot [k) is equal to a predetermined value, for example 0 amperes.

In this embodiment, the control module calculates the rotor coil voltage according to this formula:

Vrot[k-1] = -1 x (Vdc[k-1] – Vdiode), where Vdiode is a constant equal to for example 0.7V representing the voltage across diode D1.

According to one embodiment, the control module is configured to produce a stator command based on the estimated rotor current (Irot [K]).

In particular, the control module is configured in this embodiment to control the low side switches closed LS_X, LS_Y, LS_Z and the high side switches HS_X, HS_Y, HS_Z open of the electrical system SE of the stator after the estimated rotor current (Irot [k) is equal to a predetermined value, for example 0 ampere. This grounds the stator phases. According to another embodiment, the control module is configured to control the open low side switches LS_X, LS_Y, LS_Z and the closed high side switches HS_X, HS_Y, HS_Z of the electrical system SE of the stator after the estimated rotor current ( Irot [K]) is equal to a predetermined value, for example 0 ampere. In this example this puts the phases of the stator at the same potential which is at the B+ terminal.

The control of the low side closed switches LS_X, LS_Y, LS_Z and the high side switches HS_X, HS_Y, HS_Z open of the electrical system SE of the stator can be realized by a stator command sent to the control unit or directly by controlling the switches.

The invention thus makes it possible, following the request to stop the motor mode, to control the electric machine according to an estimated rotor current Irot to reduce the current drawn before the complete opening of the switches (switching elements) of the inverter. The fact of estimating the current in this way makes it possible, on the one hand, to control the setting to the potential of the phases of the stator when the coil has a very low or zero rotor current, which avoids or reduces a short-circuit at the level of the phases of the stator and therefore also torque oscillation and overvoltage. In addition, the fact of being estimated and not real makes it possible to be faster and not to be dependent on a system of measurement or calculation of real rotor current.

Indeed, the formula allows the estimated current to be close to or even equal to the actual estimated current during at least the entire beginning of the demagnetization of the rotor and at the end of the demagnetization that the calculated estimated current is more quickly close to 0 ampere than the real rotor current to reduce the time from motor mode to neutral mode.

The estimated current thus makes it possible on the one hand to avoid or reduce torque surges as well as overvoltages on the on-board network of the motor vehicle but also to be reliable and fast.

There schematically represents blocks of a diagram according to a second example of this embodiment.

The electric machine is identical to the electric machine previously described except in that it further comprises a temperature sensor, for example mounted against a winding of the stator or against a bearing of the electric machine and in that the value of the rotor resistance Rrot is estimated as a function of the measured temperature T by the temperature sensor. For example the value of the rotor resistance Rrot is according to this formula Rrot = R0(1 + αv.ΔT)

Where R0 is a value of the resistance of the rotor coil at a predetermined temperature, for example 25°C corresponding to 293.15 and ΔT is the temperature variation between the predetermined temperature and the temperature measured by the temperature sensor, for example 125° C – 25°C = 100°C and αv(K-1) is a predetermined isobaric volumetric expansion coefficient, for example equal to 0.00396.

R0 can for example be equal to 0.47 ohm and for example at 120° C. the rotor coil resistance has a value of 0.65 ohm.

Thus, in this example, the control module estimates the rotor coil current more accurately since it takes into account the rise in the resistance of the rotor coil linked to the temperature.

There schematically represents blocks of a diagram according to a third example of this embodiment

The electric machine is identical to the electric machine previously described except in that the electric machine further comprises a rotor position and rotation speed sensor and in that the control module estimates the value of the rotor coil induction Lrot as a function of an operating point of the electrical machine estimated from the estimated torque and the speed of rotation of the rotor.

The measurements of the angular position of the rotor can be carried out by means of Hall effect analog sensors and an associated magnetic target which is integral in rotation with the rotor.

According to another embodiment not shown, the control module is configured to switch from motor mode to neutral mode, a stator command depending on the setpoint torque and a predetermined torque gradient which depends on a speed of rotation of the machine electrical rotating and in that the control module commands the setting to the same potential of the stator phases when the estimated rotor current Irot is equal to or less than the predetermined value.

According to an example of this embodiment, the stator control is defined by an angle of advance between a voltage of the stator and an electromotive force of the rotating electric machine, an opening angle of switching elements of an inverter , and a ripple voltage.

According to an implementation of this second embodiment, the higher the speed of rotation of the rotary electrical machine, the lower the predetermined torque gradient.

According to one implementation of these embodiments, the motor mode stop request is generated following the expiration of a torque application delay.

According to one implementation of these embodiments, the engine mode stop request is generated following an overshoot of a temperature threshold.

According to one implementation of these embodiments, the motor mode stop request is generated following an overrun of a rotational speed threshold of the rotating electrical machine.

According to one implementation of these embodiments, the rotor command is a value of an excitation current.

The invention also relates to a method for switching from a motor mode to a neutral mode of the electric machine.

The method relates to the torque control of the electric machine during an aborted start-up phase of the heat engine.

represents a histogram graphically representing the network voltage Vdc, the electrical network current Idc, the actual rotor current Iexc [A] and Iph [A] the current of a phase of the stator according to the prior art.

represents a histogram graphically representing the network voltage Vdc, the electric network current Idc, the real rotor current Iexc [A] and Iph [A] the current of a phase of the stator of the electric machine according to the first example of the mode of achievement described above.

The method according to the invention comprises a step of estimating the rotor coil current (Irot[k) according to the formula previously described.

We can see on each histogram, a time t0 (approximately 1.125 seconds for the histogram of FIG. 6A and 0.775 seconds for the histogram of FIG. 6B), during a request to exit the motor mode of the rotating electrical machine when starting a heat engine of the motor vehicle, the engine computer transmits a corresponding instruction to the electric machine via a communication bus, as well as a setpoint torque, and a setpoint gradient. This starting of the thermal engine occurs for example within the framework of the automatic stopping and restarting function of the thermal engine according to the traffic conditions (function called STT for "stop and start" in English).

The control module commands at this instant t0 in this embodiment according to a fast demagnetization setpoint, a rotor command and a stator command according to a calculation of a setpoint torque (Tem[k]) according to this formula: Tem[k ] = Tem_0 x (Irot[k] / Irot_0)^2 to reduce the excitation current Iexc of the rotor coil as well as the current Iph in each phase of the stator. The electromagnetic torque of a Tem_0 setpoint when the control module receives the motor mode stop command setpoint is recorded to calculate Tem[k] at this time t0.

It can be seen that the current Iexc of the coil current decreases following a curve until a time t1. Time t1 (approximately at 1.195 seconds for the histogram in Figure 6A and 0.8 seconds for the histogram in Figure 6B).

At time t1, in the example of the prior art represented by the histogram of FIG. 6A, the actual rotor coil current Iexc is approximately 5 amperes, whereas in the example of the embodiment of the invention represented by the histogram of FIG. 6B, the actual rotor coil current Iexc is close to 0.5 amps.

At time t0, the control module commands the rapid demagnetization of the rotor by closing the low electronic switch Q23, opening the low output electronic switch Q24 and opening the high stage electronic switch Q1 until a time t2.

At time t2, corresponds to a step of controlling the short-circuiting of the phases of the stator in the histogram of FIG. 6A and which corresponds to a step of controlling the placing of the phases of the stator at the same potential in the histogram of FIG. 6B according to the example of the embodiment of the invention is after the estimated rotor coil current (Irot [k) is equal to 0. Indeed, the rotor coil having no current or very little current, the short-circuiting of the phases of the stator causes a current peak on the network which is very low or even zero.

We can see that from t2, if the rotor coil Lrotor carries current, as the rotor rotates and the phases of the stator are put at the same potential, this delivers a current forming a short circuit and therefore a current peak in the histogram of FIG. 6A and a very low current in the histogram of FIG. 6B and those up to a time t3.

During this period, one can see on the histogram of the prior art represented in FIG. 6A, an overvoltage Vdc which can cause disturbances on the network of the vehicle while on the histogram of FIG. 6B, there is no no or very little overvoltage due to the real excitation current close to 0 A at time t2.

Time t3 (approximately at 1.207 seconds for the histogram in Figure 6A and 0.805 seconds for the histogram in Figure 6B) corresponds to the switching of the electrical machine to neutral mode. The machine has all its bridges open. The rotor coil Lrotor is not powered and no longer restores stored energy.

The short-circuit period between t2 and t3 is 0.007 seconds for the histogram in Figure 6A and 0.003 seconds for the histogram in Figure 6B.

The short-circuit period is shorter according to the invention due to the lower current in the rotor at time t1.

Unless specified otherwise, the same element appearing in different figures has a single reference.

Claims (10)

Control module for a rotating electrical machine for a motor vehicle comprising a rotor coil (Lrotor) and phases (U, V, W) of a stator powered by an electrical network, the control module comprising a calculation program, a rotor coil voltage value (Vrot ), a rotor coil resistance value (Rrot), a rotor coil induction value (Lrot) and that the program estimates an estimated rotor coil current (Irot [k) following this formula: Irot[k] = Irot[k-1] + (Vrot[k-1] – Irot[k-1] x Rrot)/Lrot x Ts
in which:

• Irot[k-1] is the estimate of the rotor coil current previously calculated at time k-1
• Vrot [k-1] is the previous rotor coil voltage at time k-1
• Ts is the sampling time between index k-1 and index k,

and in which to switch the electric machine from a motor mode to a neutral mode, said control module is configured to command a setting to the same potential of the phases of the stator after the estimated rotor coil current (Irot [k) is equal to a predetermined value, for example 0 amperes. Control module according to the preceding claim, in which to switch from a motor mode to a neutral mode, said control module is configured to produce a stator command as a function of the estimated rotor coil current (Irot [k). Control module according to one of the preceding claims, in which the control module comprises an input of the mains voltage (Vdc) and in that the rotor coil voltage is equal to 0V or is calculated by the control module according to this formula:
Vrot[k-1] = -1 x (Vdc[k-1] – Vdiode),
Where Vdiode is a constant equal for example 0.7V. Rotating electrical machine comprising a control module according to the preceding claim, comprising:

• a rotor comprising an inductive coil,
• a stator comprising a winding having phases, and
• a rotor control unit comprising:
  • a high stage electronic switch (Q1) connected between the input of the inductive coil and the positive terminal of the network,
  • a low electronic switch (Q23) between ground and the inductive coil input,
  • a low output electronic switch (Q24) between the output of the inductive coil and ground,
  • a diode (D) comprising a cathode connected to the positive terminal of the network and an anode connected to the output of the inductive coil,

in which the rotor control unit can command, in the event of a motor mode stop command, either according to a fast demagnetization instruction, the closing of the low electronic switch (Q23), the opening of the output electronic switch bottom (Q24) and the opening of the high stage electronic switch (Q1), or according to a slow demagnetization instruction, the closing of the low electronic switch (Q23), the closing of the low output electronic switch (Q24 ) and the opening of the high floor electronic switch (Q1),
in which, in the event of a fast demagnetization setpoint, the previous rotor coil voltage is calculated according to the formula:
Vrot[k-1] = -1 x (Vdc[k-1] – Vdiode), and
in the case of a slow demagnetization setpoint, the rotor coil voltage is equal to zero. Rotating electrical machine according to the preceding claim, comprising a temperature sensor, in which the value of the rotor resistance (Rrot) is estimated as a function of the temperature measured by the temperature sensor. Rotating electrical machine according to one of the preceding claims, in which the value of the rotor coil induction (Lrot) is estimated as a function of an operating point of the machine estimated from the torque and speed. Rotating electrical machine according to one of the preceding claims, in which the control module comprises a step of transmitting a stator command and a rotor command, a setpoint torque Tem[k] according to this formula:

• Time[k] = Time_0 x (Irot[k] / Irot_0)^2
• where the rotor current Irot_0 is the estimated rotor current when the control module receives the motor mode stop command and Tem_0 is the estimated electromagnetic torque of the machine when the control module receives the command setpoint for stopping of the motor mode until the estimated rotor coil current (Irot [k) is equal to a predetermined value.

Rotating electrical machine according to one of the preceding claims, comprising a voltage converter comprising high electronic switches and low electronic switches connected to the phases of the stator and in that when the control module receives a stop command from the motor mode previously activated, the control module transmits a stator command to modify the pulse width modulation (PWM) of the high-side electronic switches and the low-side electronic switches according to the estimated rotor current (Irot k), such that the greater the estimated rotor current (Irot k is lower, the more the pulse width modulation is reduced to decrease the power supply of the stator phases in effective voltage. Method for stopping a motor mode of a rotating electrical machine for a motor vehicle according to one of the preceding claims, comprising:

• a stage for estimating the rotor coil current (Irot[K]) according to this formula: Irot[k] = Irot[k-1] + (Vrot[k-1] – Irot[k-1] x Rrot)/Lrot x Ts

in which:

• Irot[k-1] is the estimate of the rotor coil current previously calculated at time k-1
• Vrot [k-1] is the previous rotor coil voltage at time k-1
• Ts is the sampling time between index k-1 and index k,
• an engine stop command receiving step, comprising:
  • a demagnetization sub-step controlling the opening of the high stage electronic switch (Q1) and the closing of the low electronic switch (Q23), or according to a fast demagnetization instruction, by controlling the opening of the electronic switch low output (Q24), or either according to a slow demagnetization instruction, by controlling the closing of the low output electronic switch (Q24) and
  • a control sub-step for bringing the phases of the stator to the same potential after the estimated rotor coil current (Irot [K]) is equal to a predetermined value.

Method for stopping a motor mode of a rotating electrical machine for a motor vehicle according to the preceding claim, further comprising:

• a step of calculating a setpoint torque (Tem[k]) according to this formula: Tem[k] = Tem_0 x (Irot[k] / Irot_0)^2

where the rotor current Irot_0 is the estimated rotor current when the control module receives the motor mode stop command and Tem_0 is the electromagnetic torque of a setpoint when the control module receives the command setpoint from stopping the motor mode, and

• a step of controlling the rotor and the stator as a function of the setpoint torque until the estimated rotor coil current (Irot [k) is equal to a predetermined value.